00 MW机组凝汽器不锈钢管腐蚀原因分析
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摘要
某600 MW机组停机检修,对凝汽器不锈钢管机械清洗后进行汽侧灌水查漏,发现多根凝汽器管存在点蚀。经分析得出以下原因:凝汽器不锈钢管材质不满足S31708要求,具有自钝化作用的合金成分Ni、Cr、Mo达不到对应牌号的指标要求,材质耐蚀性能差;部分点蚀分布在不锈钢管正常成形位置,不锈钢管的加工质量对腐蚀造成影响;点蚀穿孔处存在腐蚀性成分富集,高含量Cl-存在于严重缺陷部位的局部蚀坑处;凝汽器管结垢,加速了垢下腐蚀的发生。
During the shutdown maintenance of a 600 MW unit,the leak detection with filling water in the steam side had been implemented after stainless steel pipes of the condensers were mechanically cleaned,and many condenser stainless steel pipes with pitting corrosion were found. The results of the cause analysis were obtained. The material quality of stainless tubes of condensers could not meet S31708 requirements,having alloy components,including Ni,Cr and Mo,with self-passivation effect,which could not meet the requirements for corresponding trademark indexes,and the corrosion resistance of the material quality was poor. Part of the pitting corrosion was distributed at the normal forming position of the stainless tubes. The processing quality of the stainless tubes resulted in corrosion. There existed corrosive component enrichment at the pitting corrosion perforation position. There existed high content of Cl-at the position of local corrosion pits having severe defects. Condenser pipes had scaling accelerated the occurrence of corrosion under the scaling.
During the shutdown maintenance of a 600 MW unit,the leak detection with filling water in the steam side had been implemented after stainless steel pipes of the condensers were mechanically cleaned,and many condenser stainless steel pipes with pitting corrosion were found. The results of the cause analysis were obtained. The material quality of stainless tubes of condensers could not meet S31708 requirements,having alloy components,including Ni,Cr and Mo,with self-passivation effect,which could not meet the requirements for corresponding trademark indexes,and the corrosion resistance of the material quality was poor. Part of the pitting corrosion was distributed at the normal forming position of the stainless tubes. The processing quality of the stainless tubes resulted in corrosion. There existed corrosive component enrichment at the pitting corrosion perforation position. There existed high content of Cl-at the position of local corrosion pits having severe defects. Condenser pipes had scaling accelerated the occurrence of corrosion under the scaling.
引文
[1]吴立新,陈方玉.现代扫描电镜的发展及其在材料科学中的应用[J].武钢技术,2005,43(6):36-40.
[2]闫洪.扫描电子显微镜和X射线显微分析原理及在镀层测试上的应用[J].机电元件,1994,14(3):27-31.
[3]于福洲.金属材料的耐腐蚀性[M].北京:科学出版社,1982:26-34.
[4]潘旭东,王向明.循环水中氯离子控制及对不锈钢腐蚀机理探讨[J].工业水处理,2013,33(3):14-15.
[2]闫洪.扫描电子显微镜和X射线显微分析原理及在镀层测试上的应用[J].机电元件,1994,14(3):27-31.
[3]于福洲.金属材料的耐腐蚀性[M].北京:科学出版社,1982:26-34.
[4]潘旭东,王向明.循环水中氯离子控制及对不锈钢腐蚀机理探讨[J].工业水处理,2013,33(3):14-15.